Power semiconductor modules with a baseplate typically have one or more circuit carriers arranged on a top side of the baseplate. The circuit carriers are populated with one or more electronic components to be cooled, wherein the waste heat arising in the components during the operation of the power semiconductor module is dissipated via the circuit carriers and the baseplate toward a heat sink by means of the module being pressed by the underside of the baseplate against the heat sink. Optionally, a heat transfer medium such as a thermally conductive paste, for example, can be introduced between the heat sink and the baseplate.
In order to achieve cooling of the components that is as effective as possible, a small distance between the baseplate and the heat sink is desirable in principle. Since the circuit carriers are usually cohesively connected to the baseplate and, if appropriate, cohesively connected to further components, flexures of the arrangement occur during the operation of the power semiconductor module on account of different coefficients of thermal expansion of the elements connected to one another, as a result of which flexures the distance between the baseplate and the heat sink can vary locally.
Moreover, during the mounting of the module on the heat sink, for example with the aid of fixing screws or other fixing elements, local stresses can occur which have the effect that the distance between baseplate and heat sink increases in regions which are somewhat further away from the relevant fixing locations.
If such thermally dictated flexures or mounting-dictated increases in distance occur below the circuit carriers, then this has the effect that the thermal transfer resistance between baseplate and heat sink increases significantly precisely in the regions having particularly high evolution of heat.